The classical American Casting Institute's stainless steel casting alloy, ACI CF-3M, is widely used for pump casings and impellers where a high degree of corrosion resistance is required. Although it is used in seawater which contains a high level of chlorides, it is known that the standard composition is susceptible to localized corrosion in the form of pitting and crevice corrosion and can be susceptible to stress corrosion cracking at temperatures over 160.degree.-180.degree. F. (71.degree. C. to 82.degree. C.). Although the beneficial effects of chromium and molybdenum on the localized corrosion resistance are well known, the effects of nitrogen and particularly the effects of the combination of chromium, nitrogen, and molybdenum have not been established.